ossfs2: set default logdir to /dev/stdout

[AlbeeSo]

What type of PR is this?

/kind bug

What this PR does / why we need it:

use /dev/stdout as default log_dir for ossfs 2.0.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[huww98]

Suggested change

	parts := strings.SplitN(option, "=", 2)
	if len(parts) == 1 {
	parts = append(parts, "")
	}
	tm[parts[0]] = parts[1]
	k, v, _ := strings.Cut(option, "=")
	tm[k] = v

But I think we should have a unified place to do the parsing. Maybe AddDefaultMountOptions can just return all the defaults, and have another func DeduplicateOptions to parse the options and remove duplications? Mount options supports escaping with \ actually. It is complicated.

[AlbeeSo]

I'm not sure if another func is needed to split the defaultMountOptions retrieving and duplications removing. It together works as AddDefaultMountOptions and it's meaningful. Maybe we can consider it if more default options need to be handled.

[mowangdk]

We need to list the default options in comments and docs

[mowangdk]

/lgtm
/approve

@AlbeeSo TODO: Add default oss parameters to docs

[k8s-ci-robot]

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